1. Field of the Invention
This invention relates to a building block system.
2. Description of the Prior Art
Various shapes of building blocks have been proposed over many years for use in building vertical and horizontal walls. A relatively common proposal is of substantially T-shaped blocks, i.e. a block consisting solely of a stem limb and a cross limb, the stem limb extending substantially perpendicularly from the middle of the cross limb, examples being disclosed in British Patent Specification No. 590,291, French Patent Specifications Nos. 1067762 and 2299468 and U.S. Pat. No. Re. 14,904. In all of these cases, the block is laid such that the cross limb extends in the general plane of the wall, whilst the stem limb extends perpendicularly to that plane.
Swedish Patent Specification No. 150829 discloses a building block which, although it appears to be substantially T-shaped when seen in front elevation and rear elevation. The block actually consists of six limbs, of which four provide the front and rear T-shapes and of which each of the other two, links one end of the cross-limb of the front T-shape with the nearer end of the cross-limb of the rear T-shape. This building block has this special shape because it is used to form ventilation or like channels in the wall.
Although substantially T-shaped blocks, when interfitted with the free end of each stem limb face-to-face with the cross limbs of two adjacent blocks, utilize the interfitting to support each other at two opposite sides of the six sides of the block, they provide no similar support at any of the other four sides.
U.S. Pat. Ser. No. 829,480 discloses a paving and building block system wherein each block consists of two block-form parts whereof a larger part protrudes from the smaller part on four sides. These blocks can interfit such that the larger parts of four outer blocks overlap the larger part of an inner block at its respective four sides. Although forces applied to the major external face of the larger part of the inner block are borne by the larger parts of the four outer blocks, forces applied to the major external face of the smaller part of the inner block are not borne by any adjacent blocks.
In the above-mentioned U.S. Pat. No. Re. 14,904, each block has the end faces of its cross limb diverging towards its stem limb, and has the lateral faces of its stem limb substantially parallel to the respective nearer end faces of its cross limb and thus diverging away from the cross limb. Moreover, those two intermediate faces of the cross limb between these respective end faces, on the one hand, and these respective lateral faces, on the other hand, converge towards the longitudinal axis of the cross limb progressing inwardly. There is thus formed a keying arrangement of substantially Z-form which, in a wall constructed from the blocks, resists forces on those faces of any one of the blocks at the major faces of the wall. However, only one shape of block with such keying arrangement is provided, so that the system is of very limited use. Although the Specification discloses use of the blocks in a vertical wall, the blocks are arranged with their cross limbs vertical and their stem limbs horizontal. Thus, a bottom layer of special blocks has to be provided if the wall is to be laid on a planar foundation.
Federal German Patent Specification No. 1926239 discloses paving slabs each of which has at each of two opposite edge sides thereof a profile including a substantially Z-form key, the profiles on most of the slabs being identical to each other. The substantially Z-form keys of each slab are arranged to extend parallel to each other in the plane of the horizontal wall formed by the slabs. However, they are offset relative to each other along the respective opposite edge sides of the slab and are thus unsuitable for use in building a vertical wall with the substantially Z-form keys extending horizontally.
French Patent Specification No. 1352121 discloses a building system employing three shapes of interfittable elements, these shapes being substantially Z, substantially T and substantially L-shaped. However, forces against the free end face of the stem limb of such T-shaped element or against the free end face of the longer limb of such L-shaped element are not borne by the adjacent elements except by way of conventional fastening means, for example riveting, used to fix the elements together.